It's the least engaging of the books so far. Lacks a sense of threat and danger and a feeling that this mission is a substantial one, to which Bond himself alludes. Feels strange when your central character is basically saying this mission isn't as hard or important as my other ones, and Fleming doesn't really manage to turn that feeling around within the story. The villains aren't engaging and the set pieces not that exciting. I'm not sure that Bond works that well tonally in America. It excels in exotic, mysterious, or cool and sophisticated places. Whereas the worlds of Las Vegas and Saratoga Springs aren't quite that.
As always though, some lovely moments and invocation of place, and Tiffany Case was a nice feisty character, but not one I'm going to remember deeply.